750 patients that are treated with transdermal Buprenorphine patches for chronic pain will be included in the study. About 20% of patients are aimed to be patch-naive, ie have received their first prescription of transdermal analgesic patches within 1 month before inclusion in this observational study. Furthermore the study should not include more than 25% of cancer patients that are treated for chronic pain in order to ensure an appropriate mix of patient population.